The present invention relates to an apparatus for controlling the rotation of an internal combustion engine.
A conventional automobile is equipped with an economy running system for improving the fuel efficiency of an internal combustion engine. The economy running system automatically stops the combustion of the internal combustion engine when the automobile is temporarily stopped at an intersection or the like. When the automobile is started again, the economy running system rotates a motor to start the internal combustion engine.
However, vibrations are generated in an automatic combustion stopping process for the internal combustion engine. The vibrations may be caused, for example, by fluctuations in torque of the internal combustion engine, or a sudden decrease in creep force. Since the automatic combustion stoppage is not intended by a driver, the driver may feel discomfort with the vibrations.
An internal combustion engine control apparatus disclosed in Laid-open Japanese Patent Application No. Hei 10-339182 maintains the rotation of an internal combustion engine with a second electric motor when a fuel is cut during deceleration of a vehicle. After the vehicle speed has been reduced to zero, the control apparatus stops the second electric motor and drives a first electric motor to prevent a difference in creep force from occurring. However, the creep force may vary to cause vibrations unless either of the two electric motors is kept driving even during stoppage of combustion of the internal combustion engine.
It is an object of the present invention to provide a control apparatus for reducing vibrations when the operation of an internal combustion engine is stopped.
To achieve the above object, the first aspect of the present invention provides a rotation control apparatus for controlling internal combustion engine rotating means for driving an internal combustion engine to control rotation of a rotating shaft of the internal combustion engine. The rotation control apparatus includes an ECU for reducing vibrations of the engine. The ECU maintains a rotational speed of the internal combustion engine at a reference rotational speed to reduce an air pressure in a cylinder of the internal combustion engine when an operation of the internal combustion engine is stopped, and subsequently stops rotation of the engine.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.